Field of the Invention
The invention relates to a centrifuge for separating a sample in the fields of medicine, pharmacy, genetic engineering, biotechnology, and so on, and particularly relates to securing strength and enhancing operability through improvement of the rigidity of a sample container for the centrifuge with a swing type rotor.
Description of Related Art
A centrifuge is a device, which includes a rotor capable of accommodating a plurality of sample containers filled with samples therein and a driving means, such as a motor, rotationally driving the rotor in a rotor chamber, and rotates the rotor at a high speed to apply a centrifugal force, so as to centrifugally separate the samples in the sample containers. Centrifuge rotors can be roughly divided into two types, i.e. angle rotor and swing rotor. In the case of the angle rotor, a plurality of tubes filled with the sample therein are accommodated in accommodation holes, and a lid is fastened to the rotor to prevent the inside of the rotor from being decompressed when windage loss reduction occurs above the opening parts of the accommodation holes and the rotor chamber is decompressed by a vacuum pump. The accommodation holes are formed at a certain fixed angle with respect to the driving shaft, and the relative angle between the accommodation holes and the driving shaft is fixed at all times regardless of the centrifugal force.
In contrast, the swing rotor has a sample container including a bucket with a bottom part, which accommodates tubes filled with the sample, a lid, which covers the inside of the bucket, and a sealing member such as an O-ring, which seals a bonding surface between the bucket and the lid, and has a rod-shaped or convex rotation shaft disposed on the bucket or the lid and engaged with rotation shaft engaging grooves formed on the rotor, so as to dispose the sample container in the rotor in a swingable manner to perform centrifugal separation. The central axis of the sample container and the driving shaft of the motor are parallel to each other (θ=0°) when the rotor is stationary. However, as the rotation speed increases, the sample container disposed in the swingable manner is affected by the centrifugal force to rotate around the rotation axis so that θ>0° , and then becomes substantially horizontal (θ≈90°) when a rotation speed that generates a centrifugal force sufficient to make the sample container horizontal is reached. Thereafter, the centrifugation ends, and θ decreases as the rotation speed drops and becomes 0° (θ=0°) when the rotation of the rotor stops. Thus, the relative angle between the central axis of the sample container and the driving shaft of the swing rotor changes according to the centrifugal force during the centrifugation. In addition, there are mainly two types of forms for holding the centrifugal load of the sample container during the centrifugation of the swing rotor. One form is that the convex parts of the rotation shaft disposed on the rotor or the bucket or the lid of the sample container are received by the opposing concave parts and the load caused by the centrifugal force of the sample container is held only by the convex parts or the concave parts. The other form is that the sample container is swung to the horizontal by the rotation shaft disposed on the rotor or the bucket or the lid of the sample container, and from there, the rotation shaft is slid in the axial direction to seat the sample container on a wall surface of the rotor, such that the load caused by the centrifugal force of the sample container is held by the rotor body (see Patent Literature 1, for example).